The prior art most pertinent to the present invention are my U.S. Pat. Nos. 4,468,239 ('239), 4,519,819 ('819) and 4,692,175 ('175). Of these patents, '239 discloses a twin tower assembly for decontaminating compressed gas in which the towers under solenoid valve and timer control of their several valves, each alternate between and together alternate in decontaminating and regenerating cycles for producing at a common outlet a constant supply of decontaminated gas. Patent '819 adds to the '239 assembly upstream of the towers a single stage precoalescer for receiving and, by coalescing, removing liquid and aerosol oil and water from contamined gas. In patent '175 the precoalescer of patent '819 is replaced by a two-stage precoalescer that removes from contaminated gas in a first stage solids and free or liquid oil and water and in a second stage oil and water aerosols, before they can reach and contaminate, clog or foul a particulate desiccant contained in the towers for absorbing moisture.
The solenoid valves of the towers are suspended from their common outlet manifold and inlet, and outlet and drain valves of each tower are opened and/or closed by actuating gas drawn as decontaminated gas from the outlet manifold. Contained in the towers in canisters, the particulate desiccant is maintained compact by a downwardly acting compactor in the upper part of each tower and actuated by decontaminated gas in that part during the tower's decontaminating cycle, while the precoalescer compensates for manufacturing tolerances by a spring acting downwardly on a canister containing its coalescers.
The present invention is particularly concerned with improving upon a twin tower-precoalescer system for decontaminating compressed gas.